False-positive exercise stress electrocardiogram due to accessory pathway in the absence of manifest preexcitation

False-positive exercise testing in patients with an accessory pathway has b een described only in patients with manifest preexcitation during exercise. We describe a patient in whom marked ST-segment changes were seen during a n exercise test in the absence of any preexcitation of the QRS complexes. T he role of the accessory pathway in producing the ST changes was reaffirmed by absence of this abnormality following catheter ablation of the accessor y pathway.